I'm bagging a '47 dodge coupe. The drivetrain is a 383 Big Block. Here's my deal I have 2 slam specialties RE-6's and 2 RE-7's. I bought the 6's and mounted them in the front because they fit. I was going to mount the 7's on the rear. keeping in mind that the bigger bags will hold up more weight at a given pressure and that more weight will be in the front the bigger bags make more sense in the front. My question is it it worth it for all the cutting that will be needed? If I leave it the way it is will the car handle like **** having the fronts running at a high PSI than the rear?
Can you get a spring rate/air volume chart for these? I have a few for the Firestone line of airsprings. Typically in the front you are shooting for 300-400 pounds per inch and about 150 on the rear if mounted directly to the axle. A bit of homework to do if you really want to do it right, or you can just guess and do it the way you want.
Please teach me El Polacko. Here is the lift/pressure chart for the RE-6 And the RE-7 Also here is the comparison chart http://www.slamspecialties.com/compare.html
Been runnin RE6's in front and RE7's in back for years with no ill effects...... Cause no, it wasnt worth all the extra effort of cutting....
You know.....I shoulda answered that without asking....and for that I do apologize... 150 PSI, I've not had the need to go any higher as I dont even use 150 PSI to get to my max up stroke. The vehicle is a 1949 chevy truck with a 1971 camaro clip up front and a triangulated 4 link out back. Nothin too trick. Ive had two different mills in the truck whilst on bags, a belly ****on 350 and a 396 both with t350's... Even with the extra weight of the 396 it still rode like a caddillac with the re6's up front...little bit higher running pressures but did fine. It now has the 350 and 4l60 in it.... Honestly it's all in the proper set up...
So I was looking around for Spring rate / AV charts and I found this article. http://www.minitruckinweb.com/tech/suspension/0904mt_maximized_air_bag_size/index.html In this aretle is states that: A large 'bag will be able to lift more weight, but will have a lower spring rate. Where a smaller 'bag will have less weight capacity but a higher spring rate. The spring rate is almost directly related to the pressure, and the weight capacity is closely ***ociated with the volume. Therefore, because a large 'bag has more volume, it takes less pressure to lift the vehicle and thus a softer spring rate and vice-versa for a smaller 'bag. So from reading this I should leave the smaller bags in the front and the bigger softer bags in the back. Correct?
An RE7 will ride better up front than an RE6, just because of air volume. But it's not necessary. I would never put an RE6 out back, especially if you are mounting it directly to the axle. It will be too firm. As for shocks, Bilstein makes some Air Ride specific shocks, but most people cringe at the thought of a $100 shock. Sometimes they do have 25% off sales though, they just had one last month.
I agree completely about putting RE-6's in the back, I've had them in the back of my '55 Fairlane (big block 429) mounted straight onto the axle, stiff as hell, unless i run it almost touching the ground....only reason I ran those was to handle the 450 HP and 520 ft lb of torque it's got....you always learn somethin the first time around.
What is going to be helpful here is to know what the weight of the car is on the front and rear axles. This will give us a load rating and height to shoot for. Say you are carrying 2150 pounds on the front wheels. To oversimplify things your springs will need to carry about 180% of that weight because of where the springs will be mounted so a bit of math means 2150# X 1.8 = 3,870 and then split in two to equal 1,935 per spring at ride height. Not having a spring rate chart directly for the spring you are using I will cross reference to the Firestone 255 style for your RE-6. http://www.firestoneindustrial.com/pdfs/industrial/datasheets/IMPERIAL_PDF/EMDG_255-1.5.pdf ... And the Firestone 224 for your RE-7 http://www.firestoneindustrial.com/pdfs/industrial/datasheets/IMPERIAL_PDF/EMDG_224.pdf Finding a spring that will hold around 2000 pounds at 300 pounds per inch spring rate at the recomended 6" installed height, the RE-7 will be the better fit for the front but the spring rate will be a bit high at 850 pounds per inch. But if you can design the spring to be at ride height at 4.5 inches high, it will hold the same weight at a lower psi and a lower spring rate which will ride a bit smoother. Realistically an even bigger spring would be a better fit to match the original ride quality. But this is the reason most air spring shops would recommend an aggressive shock (which I am in favor of anyway). These type of springs lose a bunch of efficiency in load capacity with greater internal air volumes. So the lower you can run them (physical height) the better overall. Knowing that you can design the spring pockets to fit your springs better.
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